The major objective of the proposed project is development and implementation of a comprehensive computer-based system for the control and study of drug interactions in both hospitalized and ambulatory patients. The principal goals of this program include: 1) development of appropriate computer methodology for prospective detection and prevention of undesirable drug interactions; 2) implementation of an operational computer-based drug interaction warning system suitable for use in hospitals and outpatient community pharmacies; 3) evaluation of the effects of the prototype program on drug use and health care at Stanford University Medical Center and in the surrounding community, and on the education of physicians and pharmacists about drug interactions; 4) development of technology for documentation and prospective evaluation of the clinical consequences of administering drugs which have been reported to interact, or which might be suspected of interacting, 5) investigation of potential uses of the drug interaction warning system for prevention of other adverse drug reactions in hospitalized patients, and for prospective detection and prevention of certain types of inappropriate drug therapy, and 6) development of a methodology for remote computer access to the drug interaction data base. The project employs the large, well-documented computer data base of drug interactions accumulated by the Division of Clinical Pharmacology at Stanford. Although the prototype program currently operates through the Stanford Computation time-sharing ACME facility, the project includes development of a stand-alone version of the system suitable for use in outlying hospitals; as indicated above the stand-alone system will also be capable of providing a drug interaction warning service for community pharmacies. The completed system will monitor drug use and will generate a drug interaction report whenever a newly prescribed drug interacts with a medication already being administered to the patient.